PortAudio: paex_saw.c Source File

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paex_saw.c
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1
6 /*
7 * $Id: paex_saw.c 1752 2011-09-08 03:21:55Z philburk $
8 *
9 * This program uses the PortAudio Portable Audio Library.
10 * For more information see: http://www.portaudio.com
11 * Copyright (c) 1999-2000 Ross Bencina and Phil Burk
12 *
13 * Permission is hereby granted, free of charge, to any person obtaining
14 * a copy of this software and associated documentation files
15 * (the "Software"), to deal in the Software without restriction,
16 * including without limitation the rights to use, copy, modify, merge,
17 * publish, distribute, sublicense, and/or sell copies of the Software,
18 * and to permit persons to whom the Software is furnished to do so,
19 * subject to the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be
22 * included in all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
27 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
28 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
29 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
30 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
31 */
32
33 /*
34 * The text above constitutes the entire PortAudio license; however,
35 * the PortAudio community also makes the following non-binding requests:
36 *
37 * Any person wishing to distribute modifications to the Software is
38 * requested to send the modifications to the original developer so that
39 * they can be incorporated into the canonical version. It is also
40 * requested that these non-binding requests be included along with the
41 * license above.
42 */
43
44 #include <stdio.h>
45 #include <math.h>
46 #include "portaudio.h"
47 #define NUM_SECONDS (4)
48 #define SAMPLE_RATE (44100)
49
50 typedef struct
51 {
52 float left_phase;
53 float right_phase;
54 }
55 paTestData;
56
57 /* This routine will be called by the PortAudio engine when audio is needed.
58 ** It may called at interrupt level on some machines so don't do anything
59 ** that could mess up the system like calling malloc() or free().
60 */
61 static int patestCallback( const void *inputBuffer, void *outputBuffer,
62 unsigned long framesPerBuffer,
63 const PaStreamCallbackTimeInfo* timeInfo,
64 PaStreamCallbackFlags statusFlags,
65 void *userData )
66 {
67 /* Cast data passed through stream to our structure. */
68 paTestData *data = (paTestData*)userData;
69 float *out = (float*)outputBuffer;
70 unsigned int i;
71 (void) inputBuffer; /* Prevent unused variable warning. */
72
73 for( i=0; i<framesPerBuffer; i++ )
74 {
75 *out++ = data->left_phase; /* left */
76 *out++ = data->right_phase; /* right */
77 /* Generate simple sawtooth phaser that ranges between -1.0 and 1.0. */
78 data->left_phase += 0.01f;
79 /* When signal reaches top, drop back down. */
80 if( data->left_phase >= 1.0f ) data->left_phase -= 2.0f;
81 /* higher pitch so we can distinguish left and right. */
82 data->right_phase += 0.03f;
83 if( data->right_phase >= 1.0f ) data->right_phase -= 2.0f;
84 }
85 return 0;
86 }
87
88 /*******************************************************************/
89 static paTestData data;
90 int main(void);
91 int main(void)
92 {
93 PaStream *stream;
94 PaError err;
95
96 printf("PortAudio Test: output sawtooth wave.\n");
97 /* Initialize our data for use by callback. */
98 data.left_phase = data.right_phase = 0.0;
99 /* Initialize library before making any other calls. */
100 err = Pa_Initialize();
101 if( err != paNoError ) goto error;
102
103 /* Open an audio I/O stream. */
104 err = Pa_OpenDefaultStream( &stream,
105 0, /* no input channels */
106 2, /* stereo output */
107 paFloat32, /* 32 bit floating point output */
108 SAMPLE_RATE,
109 256, /* frames per buffer */
110 patestCallback,
111 &data );
112 if( err != paNoError ) goto error;
113
114 err = Pa_StartStream( stream );
115 if( err != paNoError ) goto error;
116
117 /* Sleep for several seconds. */
118 Pa_Sleep(NUM_SECONDS*1000);
119
120 err = Pa_StopStream( stream );
121 if( err != paNoError ) goto error;
122 err = Pa_CloseStream( stream );
123 if( err != paNoError ) goto error;
124 Pa_Terminate();
125 printf("Test finished.\n");
126 return err;
127 error:
128 Pa_Terminate();
129 fprintf( stderr, "An error occured while using the portaudio stream\n" );
130 fprintf( stderr, "Error number: %d\n", err );
131 fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
132 return err;
133 }